A Birmingham MP has attacked the deportation of 12 men who were arrested over a suspected terrorist bomb plot and then released without charge as “disturbing and gravely unjust”.

In a letter to Home Secretary Jacqui Smith, Khalid Mahmood, MP for Perry Barr, and Glasgow Central MP Mohammad Sarwar, said incidents such as this do “irreparable damage” to race relations.

Apart from one British citizen, all the released men are Pakistani nationals and have been handed over to the immigration authorities to be deported, according to Number 10, on “national security” grounds.

They had been in custody since April 8 when armed police swooped on locations across North-West England.

Mr Sarwar and Mr Mahmood said they had been urged to intervene by members of the Pakistani community who “very understandably feel let down by the security forces”.

The MPs added: “We, along with many of our constituents, were amazed, shocked and indeed worried to learn that the police have been unable to present sufficient evidence to the Crown Prosecution Service on which it could lay charges against any of the 12 men arrested. Especially when these young men were initially described by both the Government and the police as having been involved in a serious terrorist plot and were arrested in such dramatic circumstances.

“We find it deeply disturbing and gravely unjust that these innocent young men, all of whom have been released without charge, are now to face immediate deportation and, therefore, will be unable to continue their legitimate academic studies which they should lawfully be entitled to complete.

“It is a very sad day when the innocent are no longer considered innocent in this country until proven guilty.”

The letter continued: “Incidents such as this do irreparable damage to the vital race relations work that is being done and has been done by the Government and leaders of ethnic minority communities, both at home in this country and abroad.

“We feel tremendously disappointed and hugely saddened by these events. There is no doubt that the security services must act upon intelligence and seek to defend fellow citizens.

“At the same time they must ensure that adequate evidence is available otherwise such events only make the task of defending our great country even harder.

“An important strand of counter-terrorism must be about winning the hearts and minds as well as the confidence of Britain’s Muslim community.

“Events such as these undermine this effort.”

The arrests took place after Bob Quick, the Met’s Assistant Commissioner and Britain’s most senior anti-terror officer, inadvertently revealed secret plans of the raid to Downing Street press photographers on his way to brief the Prime Minister.

Mr Quick has since resigned and police are adamant his error did not compromise the investigation.

On Wednesday, Lord Carlile, who reviews terror legislation, said he had decided to look into the operation while memories were still fresh.